There are several recurrent themes in the study of native speaker attitudes toward interlanguage. First among them treated in a recent review by Ludwig is comprehensibility, that is, the ease with which the native speaker can comprehend nonnative speech.' Research in the area of native speaker attitudes toward nonnative speech reviewed in Ludwig has shown that formal errors are not well related to comprehensibility of interlanguage. "Irritation" is also a topic of considerable interest. An assumption underlying the study of irritation is that even if nonnative speech is comprehensible, the form of the message may be associated with a negative affective response from the native speaker. Certain formal or mechanical errors may be considered more important than others by native speakers. The ranking of errors by comprehensibility, irritation or other criteria is referred to as an error hierarchy. An interesting, detailed example of an error hierarchy based on both comprehensibility and irritation may be found in an article by Chastain.
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